Liquid-cooled dynamoelectric machines

ABSTRACT

A liquid-cooled dynamoelectric machine wherein the rotor is enclosed by a liquid-tight nonmagnetic cylindrical shielding member and cooling liquid is sprayed directly upon hightemperature portions of the stator such as end turns of the armature winding.

United States Patent [72] inventors Appl. No. Filed Patented AssigneePriority Junpei lnagaki Yokohama-shi;

Moriyoshi Sakamoto, Yokohama-shi; Tsuneo Nakakita, Kawasaki-shi; YasuakiKanda, Tokyo; Hiroyuki Kitamura, Yokohama-shi, all of Japan Sept. 29,1969 Sept. 28, 197 1 Tokyo Shibaura Electric Co., Ltd Kawasaki-shi,Japan Oct. 1, 1968, Oct. 1, 1968, Oct. 1, 1968, Oct. 1, 1968, Oct. 1,1968 Japan 43/70871, 43/70873, 43/70874, 43/70879 mine/mm.

LIQUID-COOLED DYNAMOELECTRIC MACHINES 5 Claims, 4 Drawing Figs.

US. Cl

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[50] Field ofSearch 310/54, 57, 64, 65, 86, 168, 263, 68

[56] References Cited UNITED STATES PATENTS 2,285,960 6/1942 Fcchheimer310/54 2,573,126 10/1951 Andrus 310/86 X 3,229,130 1/1966 Drouard 310/543,309,547 3/1967 Woodward, .lr. 310/263 X 2,987,637 6/1961 Bcrtsche etal. 310/54 FOREIGN PATENTS 283,308 10/1965 Australia 310/54 693,507 9/ l964 Canada 310/86 Primary Examiner-D. F. Duggan Attorney--Flynn &Frishauf ABSTRACT: A liquid-cooled dynamoelectric machine wherein therotor is enclosed by a liquid-tight nonmagnetic cylindrical shieldingmember and cooling liquid is sprayed directly upon high-temperatureportions of the stator such as end turns ofthe armature winding.

PATENTED SEP28 19m SHEET 1 0F 2 FIG. I

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LlQUlD-COOLED DYNAMOELECTRIC MACHINES This invention relates to aliquid-cooled dynamoelectric machine and more particularly to animproved liquid-cooled dynamoelectric machine wherein cooling liquid issprayed directly upon high-temperature portions of the machine.

The prior art liquid-cooled dynamoelectric machine is constructed suchthat the cooling liquid is used to cool high-temperature portions of themachine while it is circulated through a circulating pipe contained inthe machine so that the cooling efficiency of the cooling liquid ispoor.

As is well known in the art, the rating of a dynamoelectric machine islimited by the temperature rise of the machine. For this reason, it ishighly desirable to provide an efficient cooling means for adynamoelectric machine of compact design.

One efficient method of cooling a dynamoelectric machine is to spray thecooling liquid directly upon high-temperature portions of the machine,such as end turns of a stator coil, for example. With this arrangement,however, the cooling liquid enters into the air gap between the statorand the rotor and is heated to an elevated temperature due to frictionalloss. Further, it is necessary to construct all portions of the machineliquid proof. For this reason, this type of cooling has not been used.

Electric motors for certain applications, for example, driving motors ofelectric automobiles are required to be small size, lightweight andoperable at extremely high speed. In order to improve the weight vs.output ratio to less than 1 kg./hp. like that of gasoline engines and topass very large armature current to increase the torque to more than 200percent of the rated torque when going up grades, it is highly desirableto provide an efficient cooling means.

It is an object of this invention to provide an improved liquid-cooleddynamoelectric machine in which high-temperature portions thereof can bedirectly cooled by cooling liquid.

Another object of this invention is to provide improved means whicheffectively shields the rotor and airgap against invasion of the coolingmeans.

SUMMARY OF THE INVENTION According to this invention, the rotor ofdynamoelectric machine is surrounded by a liquid-tight nonmagneticcylindrical shielding member and cooling liquid is sprayed directly uponhigh-temperature portions of the stator, such as end turns of thearmature winding. In one embodiment, such nonmagnetic shielding membersare provided between respective end plates of the stator core andstationary end members of the machine. In a modified embodiment theshielding member is a single cylinder axially extending through theairgap with its both ends connected to end members of the machine. Thecylindrical shielding member is made of laminated glass clothimpregnated with epoxide resin. The shielding member may be opened atits lower end to permit it to urge against the inner wall of the statorcore by its resiliency. Alternatively, the shielding member may becemented to the inner surface of the stator core by a suitable bondingagent.

The invention can be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a longitudinal sectional view of an electric motor embodyingthis invention;

FIG. 2 is an enlarged longitudinal sectional view of a portion of themotor shown in FIG. 1;

FIG. 3 is a view similar to FIG. 1 but employing a single shieldingmember; and

FIG. 4 is a perspective view of the nonmagnetic cylindrical shieldingmember employed in the embodiment shown in FIG. 3.

The accompanying drawings illustrate the application of this inventionfor an electric motor having a rotor of the comb type. The motorillustrated comprises a stator A and a rotor B rotatably supported bybearings C. The stator A is of the conventional construction comprisinga cylindrical frame 1, an armature core 2 secured to the inner surfaceof frame 1 and an armature winding 3 contained in the slots of thearmature core and treated with liquid-tight varnish. On the upper wallof the frame are provided nozzles 4a and 4b for spraying cooling liquid,for example oil, onto high-temperature portions of the motor which areillustrated as end turns of the armature winding 3, and exit openings 6aand 6b for draining spent cooling liquid are provided through the lowerwall of the cylindrical frame 1.

While the invention is not limited to any construction of the rotor, therotor illustrated is of the comb-shaped pole type and comprises a pairof magnetic coaxial shafts 11a and 11b which are coupled together bymeans of an intermediate nonmagnetic shaft 12. Substantially cylindricalmagnetic sections each having comb-type magnetic pole pieces 13 aresecured on shafts 11a and llb with their pole pieces 13 interrneshed asis well known in the art. Gaps between intermeshing pole pieces arefilled with nonmagnetic material 14 such as resin or cast aluminum.

Outer ends of shafts 11a and 11b are joumaled by suitable bearingsmounted in bearing brackets 22a and 22b secured to end brackets 21a and21b of the motor. End brackets 21a and 21b are provided with inwardlyprojecting cylindrical members 23a and 23b around which are wound filledcoils 24a and 24b enclosed by housings 25a and 25b. Cooling liquid iscirculated around field coils through conduits 5a and 5b extendingthrough the cylindrical frame 1.

As shown in FIGS. 1 and 2, each end plate 31 of the laminated armaturecore 2 is provided with an axially projecting annular flange 31a aroundits inner periphery to fit in one end of a nonmagnetic cylindricalshielding member 32. The shielding member is made of a laminatedcylinder of an epoxide-glass sheet, for example. A shoulder 32a isformed in one end to fit over the flange 31a of the end plate. The jointbetween the end plate 31 and the shielding member 32 is sealed in aliquid-tight manner by means of a suitable sealing compound N. Theopposite end of the shielding member 32 is connected to a stationarysupporting ring 33 secured to an end member of the motor, for example,housing 25b enclosing field coil 24b. An O-ring 34 is interposed betweenshielding member 32 and stationary supporting ring 33 to provide aliquid-tight connection.

In operation, field coils 24 a and 24b are cooled by the cooling liquidcirculating through housings 25a and 25b via conduits 5a and 5b. Coolingliquid ejected from nozzles 40 and 4b is sprayed directly upon end turnsof the armature winding 3 to effectively cool the same. Cooling liquidthen flows down along opposite sides of the armature winding. Thecooling liquid collected in the bottom of the frame 1 is dischargedthrough openings 6a and 6b.

The connection between the end plate and the shielding member may takevarious forms. For example, an annular groove may be formed on onesidewall of the end plate to receive one end of the shielding member.

According to a modified embodiment shown in FIGS. 3 and 4, thenonmagnetic cylindrical shielding member 32 is constructed to havesufficient length to axially extend between field coil housings 25a and25b. The central portion of the shielding member 32 is tightly fittedaround the inner periphery of the armature core 2 while its oppositeends are fitted over supporting rings 33 secured to field coil housings25a and 25b through O-rings 34a. Again the shielding member 32 is madeof an epoxide-glass lamination and may be opened or closed as shown bydotted lines at its lower end as shown in FIG. 4. When the lower end isleft open it is possible to firmly hold the sealing member 32 againstthe inner periphery of the armature core 2 by resilient force. Ifdesired the sealing member 32 may be cemented to the inner periphery ofthe armature core 2 by means of a suitable bonding agent. Since theshielding member has sufficiently large mechanical strength it ispossible to reduce the size of wedges which are used to hold armaturewinding 3 against radial movement. In some cases, it is possible tocompletely eliminate such wedges.

Thus, it will be seen that the invention provides a liquidcooleddynamoelectric machine wherein high temperature portions such as thearmature winding thereof are efficiently cooled by cooling liquiddirectly sprayed thereon. Moreover, as the cylindrical shield preventsthe cooling liquid from entering into the airgap and the rotor todecrease friction loss, thus preventing temperature rise of the rotor.In addition, as the cylindrical shield member is made of laminated glasscloths impregnated with cured epoxide resin, it has sufficientmechanical strength, is easy to assemble and dismount, and is notpermeable to the cooling liquid.

What we claim is:

l. A liquid-cooled dynamoelectric machine comprising:

a stator carrying an armature winding;

a rotor, an airgap being formed between said rotor and said stator;

a nonmagnetic generally cylindrical shielding member at least partiallysurrounding said rotor and extending through said airgap between saidstator and rotor, the opposite ends of said shielding member beingconnected to stationary members of said machine in a liquid-tight mannerto seal said rotor from said cooling liquid, said shielding memberincluding a cutout portion longitudinally extending along the wholelength thereof whereby said shielding member is urged against the innerperiphery of the stator member; and

means to spray cooling liquid directly upon high-tempera ture portionsof the armature winding of said stator.

2. A dynamoelectric machine according to claim 1 wherein saidnonmagnetic shielding member is comprised of glass cloth impregnatedwith cured resin.

3. A dynamoelectric machine according to claim I wherein said armaturewinding has end turns extending beyond the stator core and said coolingliquid is sprayed directly upon said extending end turns.

4. A dynamoelectric machine according to claim 3 wherein said machineincludes twostationary end members at respective ends thereof andcomprising two nonmagnetic shielding members, each being connectedbetween opposite sides of said stator and respective stationary endmembers of said machine.

5. A dynamoelectric machine according to claim 1 wherein saidnonmagnetic shielding member is cemented to the inner periphery of thestator member by means ofa bonding agent.

1. A liquid-cooled dynamoelectric machine comprising: a stator carryingan armature winding; a rotor, an airgap being formed between said rotorand said stator; a nonmagnetic generally cylindrical shielding member atleast partially surrounding said rotor and extending through said airgapbetween said stator and rotor, the opposite ends of said shieldingmember being connected to stationary members of said machine in aliquid-tight manner to seal said rotor from said cooling liquid, saidshielding member including a cutout portion longitudinally extendingalong the whole length thereof whereby said shielding member is urgedagainst the inner periphery of the stator member; and means to spraycooling liquid directly upon high-temperature portions of the armaturewinding of said stator.
 2. A dynamoelectric machine according to claim 1wherein said nonmagnetic shielding member is comprised of glass clothimpregnated with cured resin.
 3. A dynamoelectric machine according toclaim 1 wherein said armature winding has end turns extending beyond thestator core and said cooling liquid is sprayed directly upon saidextending end turns.
 4. A dynamoelectric machine according to claim 3wherein said machine includes two stationary end members at respectiveends thereof and comprising two nonmagnetic shielding members, eachbeing connected between opposite sides of said stator and respectivestationary end members of said machine.
 5. A dynamoelectric machineaccording to claim 1 wherein said nonmagnetic shielding member iscemented to the inner periphery of the stator member by means of abonding agent.